Managing the Impacts of Introduced carp dominate fish communities the Impacts of Carp Managing throughout many waterways in south- eastern Australia. They also occur in Carp Western Australia and Tasmania and have the potential to spread through many more of Australia’s water systems. Carp could eventually become widespread throughout the country. Carp are known to damage aquatic plants and increase water turbidity but their impacts on native fish species are not yet clear. Carp are also a commercial and recreational fishing resource. Managing the Impacts of Carp provides a comprehensive review of the history of carp in Australia, their biology, the damage they cause and community attitudes to these problems and their solutions. Key strategies for successful carp manage- ment are recommended by the authors who are scientific experts in carp manage- ment. These strategies are illustrated by case studies. Managing the Impacts of Carp is an essential guide for policy makers, land and water managers, carp fishers and all others interested in carp management. AGRICULTURE, FISHERIES AND FORESTRY - AUSTRALIA Managing the Impacts of Carp John Koehn, Andr ea Brumley and Peter Gehrke Scientific editing by Mary Bomfor d Published by Bureau of Rural Sciences, Canberra © Commonwealth of Australia 2000 ISBN 0 644 29240 7 (set) ISBN 0 642 73201 9 (this publication) This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Bureau of Rural Sciences. Requests and inquiries concerning reproduction and rights should be addressed to the Executive Director, Bureau of Rural Sciences, PO Box E11, Kingston ACT 2604. Published by: Copies available fr om: Bureau of Rural Sciences AFFA Shopfront PO BOX E11 GPO Box 858 Kingston ACT 2604 Canberra ACT 2601 Ph: 02 6272 4282 Phone: 02 6272 5550 Fax: 02 6272 4747 Fax: 02 6272 5771 Internet: http://www.brs.gov.au Email: [email protected] The Bureau of Rural Sciences is a professionally independent scientific bureau within the Department of Agriculture, Fisheries and Forestry – Australia (AFFA). Its mission is to provide first-class scientific research and advice to enable the department to achieve its vision — rising national prosperity and quality of life through competitive and sustainable agricultural, fisheries and forestry industries. The Commonwealth and all persons acting for the Commonwealth in preparing this booklet disclaim all responsibility and liability to any person arising directly or indirectly from any person taking or not taking action based upon the information in this booklet. Affiliations: Authors: John Koehn, Department of Natural Resources and Environment, Victoria Andrea Brumley, Forestech, East Gippsland Institute of TAFE Peter Gehrke, NSW Fisheries Office of Conservation Editor: Mary Bomford, Bureau of Rural Sciences, Canberra. Typeset by Lisa Curtin. Printed by Pirie Printers. Preferr ed way to cite this publication: Koehn, J., Brumley, A. and Gehrke, P. (2000) Managing the Impacts of Carp. Bureau of Rural Sciences (Department of Agriculture, Fisheries and Forestry – Australia), Canberra. Printed by Pirie Printers Pty limited For ewor d Carp (Cyprinus carpio) have become the The principles underlying the strategic man- most abundant large freshwater fish in agement of vertebrate pests have been Australia and are considered a problem described in Managing Vertebrate Pests: because of their perceived impacts on water Principles and Strategies (Braysher 1993) quality, soft-leaved aquatic plants and native and in Australia’s Pest Animals: New fish populations through competition and Solutions to Old Problems (Olsen 1998). The lowering habitat quality. Carp are also val- emphasis is on managing of pest damage ued by those who fish them commercially or rather than on simply reducing pest density. for recreation, and carp are used to produce The guidelines recommend that, wherever fertiliser, pet food and bait and small quanti- practical, management should concentrate ties are sold in Australia and exported to on achieving clearly defined economic or European markets for human consumption. conservation benefits. There is little reliable information about the This publication complements the National extent and nature of many of the problems Management Strategy for Carp Control caused by carp and how they can best be (NMSCC) developed by the Carp Control solved. This has led to diverse views about Coordinating Group (CCCG). The NMSCC carp management. describes a framework for a uniform national approach to the management of carp. Both Whether carp have simply taken advantage documents have been produced under the of poor habitat condition or whether they are Federal Government's Natural Heritage a cause of it is subject to much debate. The Trust. reality is probably a combination of the two. Regardless, assessing and managing the The approach to managing carp damage set impacts of carp cannot be considered in iso- out in these guidelines has been approved by lation from other water management issues. the Standing Committees on: Agriculture and Carp management is just one of many factors Resource Management; Conservation; and which influence water quality and aquatic Fisheries and Aquaculture. biodiversity. These guidelines will help policy-makers This publication is one in a series of Bureau and managers reduce the damage to water of Rural Sciences pest animal management resources and the naural environment guidelines which provides natural resource caused by carp through the use of scientifi- users, managers, advisers and funding agen- cally-based management that is humane, cies with ‘best practice’ national guidelines cost-effective, and integrated with ecologi- for managing the economic and environ- cally sustainable development. mental damage caused by carp. Others in the series include guidelines for managing feral horses, rabbits, foxes, feral goats, feral pigs, rodents and wild dogs. Peter O’Brien Executive Director Bureau of Rural Sciences Managing the Impacts of Carp iii Contents FOREWORD iii ACKNOWLEDGMENTS ix SUMMARY 1 INTRODUCTION 7 1. TAXONOMY AND HISTORY OF INTRODUCTION 11 Summary 11 1.1 Family Cyprinidae 11 1.2 Carp in Europe and Asia 12 1.3 Introduction of Cyprinids to Australia 17 1.4 Genetic strains of carp in Australia 19 2. DISPERSAL, DISTRIBUTION AND ABUNDANCE 23 Summary 23 2.1 Factors contributing to the spread of carp 23 2.2 Distribution and abundance 29 3. BIOLOGY AND ECOLOGY 33 Summary 33 3.1 General description 33 3.2 Habitats 35 3.3 Feeding behaviour and diet 39 3.4 Population dynamics 40 3.5 Ecological interactions 52 3.6 Current research 58 4. COMMUNITY ATTITUDES AND EXPECTATIONS 61 Summary 61 4.1 Attitudes from the northern hemisphere 61 4.2 Public attitudes in Australia 62 4.3 Attitudes of environmental authorities in Australia 64 4.4 Conservation groups 65 4.5 Indigenous communities 67 4.6 Animal welfare and animal rights 68 4.7 Commercial fishing industry 69 4.8 Other businesses 70 4.9 Recreational fishers 71 4.10 Carp for human consumption 74 4.11 Carp action groups and catchment management 74 Managing the Impacts of Carp v 5. ECONOMIC AND ENVIRONMENTAL IMPACTS AND COMMERCIAL USE 77 Summary 77 5.1 Introduction 77 5.2 Economic impacts 78 5.3 Environmental impact 79 5.4 Resource value and commercial use 88 6. PAST AND CURRENT MANAGEMENT 99 Summary 99 6.1 Public pressure for action 99 6.2 National management 99 6.3 State and Territory management 102 7. TECHNIQUES TO MEASURE AND MANAGE IMPACTS AND ABUNDANCE 111 Summary 111 7.1 Estimating carp abundance 111 7.2 Measuring the impacts of carp on the environment 117 7.3 Population control techniques 121 7.4 Methods for impact reduction 130 7.5 Cost of control 134 8. STRATEGIC MANAGEMENT AT THE LOCAL AND REGIONAL LEVEL 137 Summary 137 8.1 Introduction 138 8.2 Define the problem 138 8.3 Develop a management plan 139 8.4 Implementation 152 8.5 Monitoring and evaluation 152 8.6 Case studies 156 9. IMPLEMENTATION 167 Summary 167 9.1 National level 167 9.2 Government involvement 167 9.3 The regional role of extension services and catchment management 169 9.4 Group formation 169 9.5 Facilitating effective groups 170 vi Bureau of Rural Sciences 10. DEFICIENCIES IN KNOWLEDGE AND PRACTICE 175 Summary 175 10.1 Introduction 175 10.2 Populations, distribution and abundance 177 10.3 Economic impacts 178 10.4 Environmental impacts 178 10.5 Population control techniques 179 10.6 Management 182 REFERENCES 185 APPENDIX A Economic strategies for carp management 205 ABBREVIATIONS AND ACRONYMS 209 GLOSSARY 211 SCIENTIFIC NAMES 219 INDEX 225 FIGURES Figur e 1 Strategic approach to managing carp damage. 10 Figur e 2 Distribution of carp of all strains. 25 Figur e 3 Key features of carp anatomy. 34 Figur e 4 Pharyngeal teeth. 35 Figur e 5 Theoretical stock-recruitment relationship for fish populations. 43 Figur e 6 Relationship between carp recruitment and spawner abundance in New South Wales. 44 Figur e 7 Diagram of whole otolith. 45 Figur e 8 Average length and weight of carp at different ages in southern Australia. 46 Figur e 9 Predicted lengths for female and male carp at different ages from the lower Murray River. 46 Figur e 10 Results of a survey of habitats around the Paroo, Darling, Murrumbidgee and Murray Rivers. 47 Figur e 11 Decline of native fish species. 57 Figur e 12 Model of the major effects of carp on structural and process components of the aquatic environment. 82 Figur e 13 Effect of exposure time on the relationship between carp density and plant biomass remaining. 86 Figur e 14 Catches of carp and black bream in Gippsland Lakes, Victoria, from 1987–88 to 1997–98. 93 Figur e 15 Possible relationships between carp density and the damage they cause.